<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #a {
            width: 200px;
        }
        html{
            font-size: 16px;
        }
        td{
            font-size: 18px;
            padding: 2px 5px;
        }
        td div{
            width: 36px;
            height: 36px;
            border-radius: 18px;
            background-color: #d6d6d6;
            border: 1px solid #b8b8b8;
            box-sizing: border-box;
            font-size: 1rem;
            text-align: center;
            line-height: 30px;
        }
    </style>
</head>
<body>
<div id ="a">
    <p>算式：</p>
    <hr/>
    <p>结果：</p>
    <hr/>
    <table>
        <tr>
            <td><div>C</div></td>
            <td><div>CE</div></td>
        </tr>

        <tr>
            <td><div>1</div></td>
            <td><div>2</div></td>
            <td><div>3</div></td>
            <td><div>+</div></td>
        </tr>

        <tr>
            <td><div>4</div></td>
            <td><div>5</div></td>
            <td><div>6</div></td>
            <td><div>-</div></td>
        </tr>

        <tr>
            <td><div>7</div></td>
            <td><div>8</div></td>
            <td><div>9</div></td>
            <td><div>*</div></td>
        </tr>

        <tr>
            <td><div>/</div></td>
            <td><div>0</div></td>
            <td><div>.</div></td>
            <td><div>=</div></td>
        </tr>
    </table>
</div>
</body>
</html>